Electromagnetic clutch

ABSTRACT

The clutch illustrated includes electromagnetic engagement means having an integral centrifugal action arrangement for supplementing the magnetic engagement when the coil is energized and serving as the resilient means for retracting the armature plate when the coil is deenergized.

United States Patent [191 1 3,724,621 Heidorn Apr. 3, 19.73

541 ELECTROMAGNETIC CLUTCH 2,664,982 1/1954 Orzabal ..192/1os BA2,919,777 1 1960 W l ..192 84C [75] Inventor? Heidmn, Daym", 3,044,59471962 3633a ..192ls4 c 3,082,933 3/1963 Bernard .........l92/84 C X [73]Assgnee' 'l" Mom's 3,368,657 2/1968 Wrensch etafl ..192/84 c Detroit,MlCh.

[22] Filed: Dec. 27, 1971 Primary Examiner-Allan D. Herrmann pp NO:212,715 Atrorney-Warren E. Fmken et al.

[57] ABSTRACT 52] Cl 92/84 192/84 The clutch illustrated includeselectromagnetic en-v 192/105 BA gagement means having an integralcentrifugal action Cl. arr gem nt for upplementing the magnetic engage-Fleld of starch 34 34 T, 105 BA, ment when the coil is energized andserving as the 192/105 R resilient means for retracting the armatureplate when the coil is deenergized. [56]. References Cited 5 Claims, 2Drawing Figures UNITED STATES PATENTS 1,863,382 6/1932 Persons ..l92/l05BA Z5 75 .0 291d 7 77 i 2 I z :2 1 \7467 l/ I Z2554; 34 60 o g 6" W i6.96 if 0 4e #4 I! w 9a tromagnetic clutch having improved resistance toslipping at high speed without having to provide for increased magneticengagement characteristics.

A further object of the invention is to provide an electromagneticclutch wherein the conventional magnetically-actuated frictionalengagement is supplemented by an increased frictional engaging forceresulting from an integral simplified centrifugal action arrangement.

A still further object of the invention is to provide such anelectromagnetic and centrifugal clutch arrangement wherein thecentrifugal action means serves additionally as the resilient means forretracting the atmature plate when the electromagnetic coil isdeenergized.

These and other objects and advantages of the invention will beapparentwhen reference is made to the following description andaccompanying drawings, wherein:

' FIG. 1 is a fragmentary cross-sectional view of an electromagneticclutch embodying the invention; and

FIG. 2 is an end view in partial cross section taken along the plane ofthe line 2-2 of FIG. 1, and looking in the direction of the arrows.

Referring now to the drawings in greater detail, FIGS. 1 and 2illustrate an electromagnetic clutch operable through an input pulleyassembly 12 and a drive belt 14 to selectively rotate an output shaft 16for actuating an engine accessory device, such as an automobileair-conditioning compressor represented generally at 17. j

The pulley assembly 12 includes respective first and second cylindricalend portions 18 and 20 extending in opposite axial directions from anintermediate annular pulley groove 22, the latter supporting the drivebelt 14. Thecylindrical end 18 is mounted around the outer surface of acylindrical wall 23 of an electromagnetic coil housing or cover member'24, a minimal gap 25 width away therefrom. The cover member. 24 encasesan electromagnetic coil 26 between the cylindrical wall 23 and acentral-hub 27 formed on the cover member 24, with a suitable resin 28intermediate the coil 26 and the adjacent end-portion 29 of. the covermember 24. An electrical lead 30 extends through the cover member 24 toenergize the coil 26.

The hub 27 is mounted around a sleeve member 31, a minimal gap 32 widthaway therefrom. The sleeve member 31 is rotatably mounted on bearings 33which, in turn, are mounted around a central sleeve member 34 extendingfrom the compressor 17. The sleeve member 34 extends through and issecured by welding in a central opening 35 formed in a flange-likesupport member 36 operatively connected to the compressor 17. The endportion 29 of the coil cover member 24 is also secured, as by welding,to the flange member 36. The central sleeve member 34 supports theoutput shaft 16 by needle bearings 37 at the rear or compressor endthereof and by a stationary seal ring 38 mounted in a counterbore 39formed in the forward end thereof. An O-ring seal 40 is mounted aroundthe stationary seal ring 38 in a groove 42 formed in the sleeve member34. A rotating shaft seal 44 is mounted on the output shaft 16 in thecounterbore 39 and urged into contact with the stationary seal ring 38by a spring 46 supported by a spring retainer 48 mounted around I theoutput shaft 16. A retainer ring 50 mounted in an annular groove 52formed in the counterbore 39 serves as a stop for axially retaining thestationary seal ring 38 within the sleeve member 34.

A pair of retainer rings 54 and 56, mounted on the sleeve members 31 and34, respectively, adjacent one end of the bearings 33 and shoulders 58and 60 formed on the sleeve members 31 and 34, respectively, ajdjacentthe other end of the bearings 33, serve to retain the respectivecooperating members in axial relationship with the output shaft 16.

A magnetic pole member 62 is secured at a plurality of spaced bosses 64(FIG. 2) formed around the outer periphery thereof to the inner surfaceof the-second cylindrical end portion 20 of the pulley assembly 12 inany suitable manner, such as Welding, and further secured at spacedbosses 65 (FIG. 2) formed around a I central opening 66 thereof to theforward end of the sleeve member 31 adjacent a collar 68 formed on thelatter. The pole member 62 is thus positioned radially within thecylindrical end portion 20 of the pulley assembly .12 adjacent thepulley groove 22.As a result of the spaced bosses .64, there is formed aplurality of arcuate-shaped annular spaces or passages 70 (FIG. 2)intermediate the cylindrical pulley end portion 20 and the pole member62. There also results a plurality of arcuate-shaped annular spaces7Iintermediate the pole member 62 and the sleevemember 31 by virtue ofthe location of the bosses 65. A plurality of equally-spaced arcuateslots 72 (FIG. 2) are formed around an-intermediate portion of thepolemember 62.

An armature plate 74, formed of three equal-size arcuate segments 74a,74b, and 74 (FIG. 2 is shown in a deenergized position in FIG. 1. Thethree-segment armature plate 74 is positioned adjacent the pole memberarmature plate segments 74a,74b, and 740 extending adjacent the innersurface of the second cylindrical end portion 20 of the pulleyassembly12, there being a variable-width annular gap 77 therebetween.Two concentric rows of equally-spaced arcuate slots 78 are formed ineach of the armature plate segments 74a, 74b, and 74c, located radiallyinward and outward of the adjacent arcuate slots 72 formed in the polemember 62.

Cylindrical flange or hub segments 79, each having a radial slot 80formed therein are formed on the armature plate 74. A hub member 82 is:mounted on the first reduced end portion of the output shaft 16, with aspacing ring 84 provided between the inner end of the hub member 82 anda shoulder 86 formed on the output shaft 16. The hub member 82 is keyedto the output shaft 16 by a suitable key 88 and is retained in place byan inner nut 90 .threadedly mounted on threads 92 formed on the extendedend of the output shaft 16 and abutting at one end thereof against ashoulder 94 formed on an inner surface of the hub member 82. An outerlock nut 96, having a collar 98 formed on an end thereof, is threadedlymounted on threads 99 formed on the outer surface of the hub member 82,the collar 98 abutting against the outermost end face of the inner nut90.

A centrifugal force-responsive member 100 includes a body portion 102(FIG. 2) mounted on the hub member 82 for rotation therewith. Threesubstantially tangentially extending leg segments 104 are formed on thebody portion 102, each including an intermediate twisted portion 106 anda bent end portion 108, with the latter extending through the radialslots 80 of the cylindrical flange 79. The end portions 108 areresiliently retained in the slots 80 by molded rubber members orgrommets 110.

OPERATION In operation, the clutch is engaged by the energization of theelectromagnetic coil 26 which causes magnetic flux to traverse a paththrough the adjacent paramagnetic materials, as indicated by thedot-dash line 112 (FIG. 1). More specifically, the path of the flux isfrom the coil 26' into side wall 29 portion of the cover member 24,thence across the gap 25 into the first cylindrical end portion 18 andaround the pulley groove 22 to the second cylindrical end portion 20,then across the adjacent progressively closing annular gap 77 to reachthe cylindrical wall segments 76 formed on the armature-plate 74, fromwhence it crosses the radially extending gap75 to the radial outerportion of the magnetic pole member 62. A plurality of poles result fromthe spaced relationship of the alternately located arcuate slots 70, 71,72, and 78 formed in and radially adjacent the pole member 62 and thearmature plate 74, the flux alternately crosses the gap 75 to theintermediate portion of the armature plate 74 and thence back across thegap 75 to the intermediate portion of the magnetic pole member 62, andthrough the gap 75 once again to the radial inner portion of thearmature plate 74 and back to the sleeve member 31 from whence the fluxcrosses the gap 32 to the adjacent hub member 27 to complete thecircuit. Some flux bypasses the path just described by crossing into thesupport bosses 64 and 65. These areas become saturated as a result ofexcess flux being available from the coil 26. This arrangement providesa strong magnetic attraction which draws the armature plate 74 bothaxially toward the pole member 62 and radially outwardly toward thepulley cylindrical end portion 20. The resultant axial and radialface-to face engagement forces cause the member 100, through the legsegments 104, to rotate the output shaft 16 to thus drive the compressor17.

It should be noted at this point that the leg segments 104 serve asresilient members which are able to give" while the armature plate 74moves through the adjacent gap 75 to contact the pole member 62 byvirtue of their shapes and the twisted connection with the body portion102. It may thus be realized that, once the coil 26 is deenergized,nulling the magnetic attraction between the members 62 and 74, theresilient leg segments 104 will return to their original positionsreestablishing the predetermined gap 75 width between the armature plate74 and the pole member 62.

ated engagement process and that any slip between the armature and polemembers 74 and 62, respectively, which may tend to occur as a result ofincreased pulley 12 speed is substantially offset by the resultantincreased tendency of the wall segments 76 to more tightly engage thecylindrical end portion 20 of the pulley assembly 12. Hence, there areboth radial and annular locations at which frictional engagement isaccomplished due to energization of the coil 26, and an annulararrangement whereby centrifugally-actuated frictional engagement occurs.

While but one embodiment of the invention has been shown and described,other modifications thereof are possible.

I claim:

l. A magnetic clutch comprising an input member, an output shaft, abearing concentric to said output shaft, a cover member mounted adjacentsaid input member, an electromagnetic coil mounted in said cover member,a first clutch element secured to said input member, a sleeve membersecured to said first clutch element and extending axially within saidcover member and being rotatably mounted on said bearing, a secondclutch element, mounting means for mounting said second clutch elementon said output shaft adjacent said first clutch element and providinglimited axial and radial movements of said second clutch elementrelative to said first clutch element and said input member,respectively, upon energization of said electromagnetic coil.

2. The magnetic clutchdescribed in claim 1, wherein said mounting meansincludes a hub portion mounted on said output shaft, and a plurality ofresilient leg segments formed on said hub portion and extendingsubstantially tangentially from said hub portion with respect to saidoutput shaft and operatively connected to said second clutch element,said resilient leg segments serving to permit said second clutch elementto move outwardly under the action of centrifugal force to supplementthe magnetic attraction between said first and second clutch elementswhen said coil is energized and serving as the retraction means forretracting said second clutch element when said coil is deenergized.

3. The magnetic clutch described in claim 2, and resilient meansinterconnecting said resilient leg segments and said second clutchelement.

4. A magnetic clutch comprising a housing, an input pulley freelymounted at one end thereof around said housing, an output shaftprotruding from said housing and rotatable relative to said housing, anelectromagnetic 'coil mounted in said housing, a pole member secured tosaid input pulley adjacent the other end thereof, circumferentiallyspaced armature plate segments operatively connected to said outputshaft for rotation therewith, said armature plate segments being locatedadjacent said pole member a predetermined gap width away therefrom,flange segments formed on the outer periphery of said armature platesegments radially inward of said other end of said input pulley, andcentrifugal means operatively connected between said armature platesegments and said output shaft for permitting said armature platesegments to move radially outwardly toward said other end of said inputpulley under the action of centrifugal force to supplement the magneticattraction between said armature plate segments and both of said poleand pulley members when said coil is energized.

5. A magnetic clutch comprising a cover member, an input pulley havingfirst and second cylindrical end portions formed on opposite endsthereof and freely mounted at said first cylindrical end portion thereofaround said cover member, an output shaft protruding from said covermember and rotatable relative to said cover member, an electromagneticcoil mounted in said cover member, a pole member, secured to said inputpulley adjacent the other end thereof, a sleeve member connected to theradially inner portions of said pole member and extending axially'withinsaid cover member, said cover member, input pulley, pole member andsleeve member cooperating to form a clutch housing, a bearing concentricto said output predetermined gap width away therefrom, a flange portionformed on the outer periphery of each of said armature plate segmentsradially inwardly of said second cylindrical end portion of said inputpulley, a 'hub member mounted on said output shaft, substantiallytangentially extending leg members formed on said hub member andresiliently connected to said armature plate segments for permittingsaid armature plate segments to move both axially and radially outwardlytoward said second cylindrical end portion of said input pulley underthe action of centrifugal force to supplement the magnetic attractionbetween said armature plate segments and both of said pole member andsaid second cylindrical end portion when said coil is energized and toaxially withdraw said armature plate segments from said pole member whensaid coil is deenergized.

1. A magnetic clutch comprising an input member, an output shaft, abearing concentric to said output shaft, a cover member mounted adjacentsaid input member, an electromagnetic coil mounted in said cover member,a first clutch element secured to said input member, a sleeve membersecured to said first clutch element and extending axially within saidcover member and being rotatably mounted on said bearing, a secondclutch element, mounting means for mounting said second clutch elementon said output shaft adjacent said first clutch element and providinglimited axial and radial movements of said second clutch elementrelative to said first clutch element and said input member,respectively, upon energization of said electromagnetic coil.
 2. Themagnetic clutch described in claim 1, wherein said mounting meansincludes a hub portion mounted on said output shaft, and a plurality ofresilient leg segments formed on said hub portion and extendingsubstantially tangentially from said hub portion with respect to saidoutput shaft and operatively connected to said second clutch element,said resilient leg segments serving to permit said second clutch elementto move outwardly under the action of centrifugal force to supplementthe magnetic attraction between said first and second clutch elementswhen said coil is energized and serving as the retraction means forretracting said second clutch element when said coil is deenergized. 3.The magnetic clutch described in claim 2, and resilient meansinterconnecting said resilient leg segments and said second clutchelement.
 4. A magnetic clutch comprising a housing, an input pulleyfreely mounted at one end thereof around said housing, an output shaftprotruding from said housing and rotatable relative to said housing, anelectromagnetic coil mounted in said housing, a pole member secured tosaid input pulley adjacent the other end thereof, circumferentiallyspaced armature plate segments operatively connected to said outputshaft for rotation therewith, said armature plate segments being locatedadjacent said pole member a predetermined gap width away therefrom,flange segments formed on the outer periphery of said armature platesegments radially inward of said other end of said input pulley, andcentrifugal means operatively connected between said armature platesegments and said output shaft for permitting said armature platesegments to move radially outwardly toward said other end of said inputpulley under the action of centrifugal force to supplement the magneticattraction between said armature plate segments and both of said poleand pulley members when said coil is energized.
 5. A magnetic clutchcomprising a cover member, an input pulley having first and secondcylindrical end portions formed on opposite ends thereof and freelymounted at said first cylindrical end portion thereof around said covermember, an output shaft protruding from said cover member and rotatablerelative to said cover member, an electromagnetic coil mounted in saidcover member, a pole member, secured to said input pulley adjacent theother end thereof, a sleeve member connected to the radially innerportions of said pole member and extending axially within said covermember, said cover member, input pulley, pole member and sleeve membercooperating to form a clutch housing, a bearing concentric to saidoutput shaft for rotatably supporting said sleeve member, an armatureplate including a plurality of circumferentially spaced segments, saidarmature plate segments being located adjacent said pole member apredetermined gap width away therefrom, a flange portion formed on theouter periphery of each of said armature plate segments radiallyinwardly of said second cylindrical end portion of said input pulley, ahub member mounted on said output shaft, substantially tangentiallyextending leg members formed on said hub member and resilientlyconnected to said armature platE segments for permitting said armatureplate segments to move both axially and radially outwardly toward saidsecond cylindrical end portion of said input pulley under the action ofcentrifugal force to supplement the magnetic attraction between saidarmature plate segments and both of said pole member and said secondcylindrical end portion when said coil is energized and to axiallywithdraw said armature plate segments from said pole member when saidcoil is deenergized.